Behavioral responses of the woolly whitefly Aleurothrixus floccosus (Hemiptera: Aleyrodidae) to volatile organic compounds emitted from Citrus at laboratory conditions

Insects use biogenic volatile organic compounds (BVOCs) as chemical cues to find their host plants and colonize them. Studies of olfactory responses have reported that BVOCs released by host plants attract whiteflies. The citrus woolly whitefly, Aleurothrixus floccosus (Maskell) (Hemiptera: Aleyrodidae) is a serious foliar pest, infesting citrus orchards at the Pica Oasis, Tarapaca Region, Chile. We studied the attractant behavior of A. floccosus toward BVOCs emitted from lime (Citrus xaurantiifolia (Christm.) Swingle), mandarin (Citrus reticulata Blanco), and tangelo (Citrus reticulata x Citrus xparadisi Macfad.) shoots. We collected volatiles from living plants using dynamic headspace technique for 24 h. The BVOCs released by the Citrus species were collected on Porapak Q traps and analyzed by gas chromatography coupled to mass spectrometry (GC-MS). The chemical analysis revealed differences in abundances of monoterpenes, sesquiterpenes and aldehydes; thus, D-limonene (33.44%) was the most abundant compound in lime and significantly higher than mandarin and tangelo. On the other hand, sabinene (12.36%), nonanal (28.06%) and caryophyllene (22.97%) were more abundant in mandarin. Tangelo showed high abundance of beta-phellandrene (17.01%), nonanal (17.87%) and caryophyllene (16.01%). In the two-choice bioassays, we found 13.5% and 17.1% more A. floccosus females in lime than in mandarin and tangelo, respectively. Our findings show that the volatile profile of 'Limon de Pica', C. aurantiifolia, elicits the strongest attractive behavior of A. floccosus females in the olfactometry experiments.

Automated summary

In this study, it was found that different citrus species emit varying levels of biogenic volatile organic compounds (BVOCs) that result in different attractive behaviors towards the citrus woolly whitefly, A. floccosus. Specifically, the compound D-limonene from lime showed the strongest attractive behavior in olfactometry experiments.